The aims of this project are to determine the primary biosynthetic pathway(s), intracellular transport systems (e.g., intracellular protein carriers), storage events associated with lamellar bodies, the mechanism of secretion at the cell surface, and the regulation of pulmonary surfactants in alveolar type II cells. Unlike earlier investigations in this field in which results were based on heterogeneous lung cell preparations and lavage, our studies are being done with homogeneous populations of alveolar type II cells of adenomas induced by urethan injection and in cell cultures of the type II cells derived from the adenomas and from normal rat lung. Our series of experiments will determine whether pulmonary surfactants and the enzymes involved in their synthesis in type II cells exhibit an asymmetric distribution in microsomal vesicles. Monolayer cultures of alveolar type II cells from adenomas and normal lung will be set up for investigation of regulatory factors that control surfactant secretion. Studies of the quantitative importance and properties of key enzymes involved in surfactant metabolism of microsomes and lamellar bodies are currently under investigation.